Plunger lock with compensating spline

ABSTRACT

A plunger lock in which overall size is reduced by elimination of one of the basic pieces employed with prior locks of this type. Included in the subject lock is a cylindrical housing for mounting on an enclosure to be locked and serving the function of both the external housing and intermediate shell employed in prior locks. Disposed within the cylindrical housing is a plug that experiences angular motion between trapped and released positions and axial motion between locked and unlocked positions only when in the released position. Tumblers within the plug engage a spline in the housing to thereby retain the plug in the trapped position until released by insertion of a proper key. Because of the relative axial movement required between the plug and the housing and since the overall length of the lock is limited by use requirements, the first locking wafers in the plug actually lie outside the housing with the plug in the outward or locked position. To compensate for this factor, a U-shaped spline shell is provided that moves axially with the plug and is thereby in an extended position to receive the exposed wafers.

United States Patent Patriquin Oct. 7, 1975 [54] PLUNGER LOCK WITH COMPENSATING [57] ABSTRACT SPLINE A plunger lock in which overall size is reduced by [75] Inventor: George P. Patriquin, Gardner, Mass. elimination of one of the basic pieces employed with prior locks of this type. Included in the subject lock is [73] Asslgnee' Hudson Lock Hudson Mass a cylindrical housing for mounting on an enclosure to [22] Filed: Nov. 11, 1974 be locked and serving the function of both the external housing and intermediate shell employed in prior [211 App! 522645 locks. Disposed within the cylindrical housing is a plug that experiences angular motion between trapped and {52] US. Cl 70/360; 70/DIG. 79 released positions and axial motion between locked [51] Int. Cl. E05B 29/02 and unlocked positions only when in the released posi- [58] Field of Search 70/360, 361, 100, 455, tion. Tumblers within the plug engage a spline in the 70/99, 81, DIG. 79 housing to thereby retain the plug in the trapped position until released by insertion of a proper key. Be- [56] References Cited cause of the relative axial movement required between UNITED STATES PATENTS the plug and the housing and since the overall length 2,116,965 5/1938 Schoorel 70/38 lock l by use requ'renlems h first 2,573,061 0/1957 Raymondum 70/360X lock ng wafers 1n theplug :actually he outslde the 3,102,411 9/1963 Fn-edmamn 70/1O0 housmg w1th the plug 1n the outward or locked pos1- 3 3 90 9 2 josephamm 70/90 tion. To compensate for this factor, a U-shaped spline 3,744,283 7/1973 Schmidt 70/361 X hell i provided hat m ves axially with he plug and is thereby in an extended position to receive the ex- Primary ExaminerRobert L. Wolfe posed wafers. Attorney, Agent, or FzrmJohn E. Toupal 9 Claims, 6 Drawing Figures /9 7 l l A r": 1 I l a /7 US. Patent Oct. 7,1975 3,910,082

PLUNGER LOCK WITH COMPENSA'IING SPLINE BACKGROUND OF THE INVENTION This invention relates generally to plunger locks and, more particularly, to a plunger lock with an axially movable spline.

The plunger lock is a well-known device in which an inward push on a plug head produces a similar movement of a rearward plunger which afiects locking or unlocking operations. The conventional plunger lock is composed of three basic parts: a cylindrical housing for mounting in an enclosure to be secured, a shell axially slidable within the housing and a key receiving plug rotatable within the shell in response to operation by a proper key but having a fixed axial relationship thereto. Examples of typical plunger locks are disclosed, for example, in U.S. Pat. No. 3,102,411 and in the present applicant's copending U.S. Pat. application Ser. No. 364,874 filed May 29, 1973.

Although it fulfills certain special locking requirements, the conventional plunger lock has the disadvantage of an outside housing diameter substantially greater than that of the normal cam lock thus negating the sometimes desirable possibility of interchange with cam locks on various structures to which they both may be applied. In addition, the increased size and elimination of one component inherently results in additional cost. A simple reduction in the size of the plunger locks individual components to alleviate these problems is not acceptable in that such action will compromise the overall security provided by the lock.

The object of this invention, therefore, is to provide a plunger lock that is compatible in size to conventional cam locks and which exhibits a security level equal to that of prior plunger locks.

SUMMARY OF THE INVENTION The present invention provides a plunger lock in which overall size is reduced by elimination of one of the basic pieces employed with prior locks of this type. Included in the subject lock is a cylindrical housing for mounting on an enclosure to be locked and serving the function of both the external housing and intermediate shell employed in prior locks. Disposed within the cylindrical housing is a plug that experiences angular motion between trapped and released positions and axial motion between locked and unlocked positions only when in the released position. Tumblers within the plug engage a spline in the housing to thereby retain the plug in the trapped position until released by insertion of a proper key. Because of the relative axial movement required between the plug and the housing and since the overall length of the lock is limited by use requirements, the first locking wafers in the plug actually lie outside the housing with the plug in the outward or locked position. To compensate for this factor, a U- shaped spline shell is provided that moves axially with the plug and is thereby in an extended position to receive the exposed wafers. The spline shell has outer surfaces that conform to and are axially slidable within the surfaces of an axial spline defined by the inner surface of the cylindrical housing. A spring member extending between the housing and the spline shell exerts thereon a force urging the spline shell against a stop surface on the plug. Thus, the spline shell is forced into the axial spline on the housing in response to inward movement of the plug and is moved out of the axial spline by the spring member in response to outward movement of the plug.

Another feature of the invention is the provision of a resilient plastic sleeve positioned around the head portion of the plug. Retaining the resilient sleeve in position is a reentrant annular rim that engages an inwardly disposed shoulder on the plug. The resilient sleeve provides weather protection for the exposed innards of the lock when the plug is in the locked outward position.

DESCRIPTION OF THE DRAWINGS These and other features and objects of the present invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a cross sectional side view of a lock according to the present invention:

FIGS. 2 and 4 are cross sectional views taken along the lines 2-2 and 4-4 of FIG. 1;

FIG. 3 is a cross sectional view taken along lines 3-3 of FIG. 6;

FIG. 5 is a perspective view of the spline shell shown in FIGS. 1--3; and

FIG. 6 is a cross sectional view illustrating the lock shown of FIG. 1 in a different position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1-3 there is shown a plunger lock 11 including a hollow cylindrical housing 12 having external threads 13 for mounting to an enclosure (not shown) to be secured. Positioned within the hous ing 12 is a plug 15 (shown in elevation in FIG. 1) including the body portion 16 straddled by a head portion 17 and a plunger portion 18. The body portion 16 retains conventional outwardly biased wafer tumblers 19 that can be withdrawn into the plug by insertion of a proper key into a keyway having an entrance in the head portion 17. In response to axial movement of the plug 15, the plunger 18 performs locking and unlocking operations on a conventional latch mechanism (not shown).

Extending laterally from the plunger 18 is a longitudinally disposed, stepped rib 21 having a rear guide portion 22 and an elevated stop portion 23. The plunger 18 is accommodated by a central opening 25 in a rear wall 26 of the housing 12. Extending the opening 25 outwardly is an arcuate opening 27 that terminates at one end in a radially enlarged slot 28. As shown in the Figures, the guide portion 22 is accommodated by the arcuate opening 27 and engages the end surfaces 29 and 30 thereof to limit angular motion of the plug 15 within the housing 12. A compression spring member 31 extends between the inner surface of the bottom wall 26 and the body portion 16 of the plug 15. Inward axial motion of the plug against the spring 31 is prevented by engagement between the stop portion 23 and the inner surface of the bottom wall 26 except when the plug 15 is rotated into a released position wherein the stop portion 23 can be received by the enlarged slot 28.

Included in the head portion. of the plug 15 is an annular plastic cover 32 having a cylindrical wall portion 33 that is press fitted over the outer surface of the head 17 and a reentrant rim 34 that contacts an inwardly turned shoulder 35 that joins the head portion 17 to the body portion 16. Formed in the inner surface of the housing 12 is an axial spline 36 that retains a U-shaped spline shell 37 that receives the wafers 19. The outer surfaces of the spline shell 37 conform to the surfaces defining the axial spline 36 so as to guide axial movement thereof as described hereinafter. However, the engagement between the side walls 38 of the shell 37 with the adjacent surfaces 39 of the axial spline 36 prevent angular motion of the shell 37 relative to the housing 12. A spring member 41 with one end contacting an end wall 42 of the axial spline 36 urges the spline shell 37 against the annular rim 34 on the head portion 17. Also formed in the inner surface of the housing 12 is an auxiliary spline 40 that permits removal of the key with the lock in an unlocked position and complementary splines 36' and 40' spaced 180, respectively, from splines 36 and 40. The complimentary splines 36' and 40 accept opposite ends of the wafers 19 during insertion of a key.

FIG. 1 shows the lock 11 in a locked condition with the head portion 17 extending out of the housing 12, the plunger 18 partially withdrawn into the housing 12 and the wafers l9 trapped within the spline shell 37 so as to prevent angular motion of the plug 15. In that position it will be noted that the spline shell 37 includes an exposed length portion 47 that has been moved out of the axial spline 36 by the spring member and retains and traps the first two wafers in the plugs body portion 16. In addition, weather protection for the innards of the plug 15 is provided by the resilient cover 32.

Insertion of a proper key into the plug 15 withdraws the wafers 19 to shear in the conventional manner and thereby allows angular motion of the plug 15 within the housing 12. This angular motion is counterclockwise as viewed in FIG. 2 and proceeds to a release position wherein the front guide portion 22 engages the end wall 30 of the arcuate opening 27. In that position the enlarged slot 28 accommodates the elevated stop portion 23 and the entire plug 15 can be pushed axially into an unlocked position wherin the plunger 18 releases a suitable latch (not shown). During this movement the head portion 17 forces the exposed portion 47 of spline shell 37 into the axial spline 36 as shown in FIG. 5. When inward force is removed, the spring 31 forces the plug 15 back into the locked position wherein a pin 51 in the plunger 18 engages the end wall of the housing 12. Relocking is then performed by causing a proper key to withdraw the wafers 19 and rotate the plug 15 (in a clockwise direction as shown in FIG. 2) to the trapped position wherein the front guide portion 22 engages the end wall 29 of the arcuate opening 27. In that position the wafers 19 again project from the plugs body portion 16 and are trapped within the spline shell 37 which has been forced outwardly by the spring 41 to the position shown in FIG. 1.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.

What is claimed is:

l. A lock comprising:

a cylindrical housing for mounting on an enclosure to be locked, said cylindrical housing comprising an inner surface that defines an axial spline;

a plug means mounted for angular motion within said cylindrical housing between trapped and released positions and for axial motion therein between locked and unlocked positions only in said released position, said plug means defining a keyway for receiving a proper key;

a spline shell means disposed within said axial spline and axially movable therein; said spline shell means and said axial spline having engaging surfaces that prevent relative angular motion therebetween;

bias means for producing axial movement of said spline shell means withn said axial spline in response to axial movement of said plug means within said cylindrical housing; andv tumbler means mounted in said plug means and having portions normally biased into and engaging said spline shell means with said plug means'in said trapped position so as to prevent angular motion thereof within said cylindrical. housing, said tumbler portions being removable from said spline shell means to allow rotation of said plug means to said released position in response to insertion of a proper key into said keyway.

2. A lock according to claim 1 wherein with 'said plug means in said locked position, said spline shell comprises an exposed longitudinal portion that projects axially out of both said axial spline and cylindrical hous- 3. A lock according to claim 2 wherein said exposed portion of said spline shell receives and engages said tumbler means with said plug means in said trapped position.

4. A lock according to claim 3 wherein said spline shell is U-shaped with outer surfaces that conform to the surfaces of said axial spline.

5. A lock according to claim 4 wherein said exposed portion of said spline shell is received by said axial spline with said plug means in said unlocked position.

6. A lock according to claim 5 wherein said plug means comprises a stop that contacts said exposed por-- tion of said spline shell, and said bias means comprises a spring member extending between said housing and said spline shell and exerting a force thereon toward said stop such that said spring member induces movement of said exposed shell portion out of said axial spline in response to axial movement of said plug means toward said locked position and said stop urges said exposed shell portion into said spline in response to axial movement of said plug means toward said unlocked position.

7. A lock according to claim 1 wherein the entrance to said keyway is at one end of said plug means, and said one end moves out of said cylindrical housing in response to axial movement of said plug means in one direction and into said cylindrical housing in response to axial movement of said plug means in the opposite direction.

8. A lock according to claim 7 including a resilient sleeve positioned around said one end of said plug means.

9. A lock according to claim 8 wherein said one end of said plug means includes an annular inwardly disposed shoulder joined to the remaining portion of said plug means, and said resilient sleeve includes an annu- 

1. A lock comprising: a cylindrical housing for mounting on an enclosure to be locked, said cylindrical housing comprising an inner surface that defines an axial spline; a plug means mounted for angular motion within said cylindrical housing between trapped and released positions and for axial motion therein between locked and unlocked positions only in said released position, said plug means defining a keyway for receiving a proper key; a spline shell means disposed within said axial spline and axially movable therein; said spline shell means and said axial spLine having engaging surfaces that prevent relative angular motion therebetween; bias means for producing axial movement of said spline shell means withn said axial spline in response to axial movement of said plug means within said cylindrical housing; and tumbler means mounted in said plug means and having portions normally biased into and engaging said spline shell means with said plug means in said trapped position so as to prevent angular motion thereof within said cylindrical housing, said tumbler portions being removable from said spline shell means to allow rotation of said plug means to said released position in response to insertion of a proper key into said keyway.
 2. A lock according to claim 1 wherein with said plug means in said locked position, said spline shell comprises an exposed longitudinal portion that projects axially out of both said axial spline and cylindrical housing.
 3. A lock according to claim 2 wherein said exposed portion of said spline shell receives and engages said tumbler means with said plug means in said trapped position.
 4. A lock according to claim 3 wherein said spline shell is U-shaped with outer surfaces that conform to the surfaces of said axial spline.
 5. A lock according to claim 4 wherein said exposed portion of said spline shell is received by said axial spline with said plug means in said unlocked position.
 6. A lock according to claim 5 wherein said plug means comprises a stop that contacts said exposed portion of said spline shell, and said bias means comprises a spring member extending between said housing and said spline shell and exerting a force thereon toward said stop such that said spring member induces movement of said exposed shell portion out of said axial spline in response to axial movement of said plug means toward said locked position and said stop urges said exposed shell portion into said spline in response to axial movement of said plug means toward said unlocked position.
 7. A lock according to claim 1 wherein the entrance to said keyway is at one end of said plug means, and said one end moves out of said cylindrical housing in response to axial movement of said plug means in one direction and into said cylindrical housing in response to axial movement of said plug means in the opposite direction.
 8. A lock according to claim 7 including a resilient sleeve positioned around said one end of said plug means.
 9. A lock according to claim 8 wherein said one end of said plug means includes an annular inwardly disposed shoulder joined to the remaining portion of said plug means, and said resilient sleeve includes an annular reentrant rim that engages said shoulder. 